16qam星形和矩形星座图调制解调matlab代码

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1、 %% ------------------------------------------------------------ % 软件无线电课程设计 % % 方形、星形16QAM调制解调仿真 % %%------------------------------------------------------------ %%主程序 clc clear %% 定义参数 fd=250*10^6; %码元速率250M fs=2500*10^6; %滤波器采样率 fc=2500*10^6; %载

2、波频率2.5G f=10000*10^6; %对载波采样 data_len=200000; %数据长度 sym_len=data_len/4; %码元序列长度 M_QAM=16;%QAM数 k=log2(M_QAM); SNR=1:12;%白噪声信噪比, %% ------------------------------------------------------------ bit_tx=randint(1,data_len);%产生随机序列 echo off; rec_qam16=QamMod(bit_tx,16);

3、 %方形16QAM调制 star_qam16=SrarQamMod(bit_tx); %星形16QAM调制 base_rec=base_shape(fd,fs,f,rec_qam16); %基带成型滤波 base_star=base_shape(fd,fs,f,star_qam16); %基带成型滤波 for i=1:length(SNR) %信噪比从1dB到12dB计算误码率 SNR_=i %方形映射16QAM rf_rec_qam1

4、6=CarrierMod(fc,f,base_rec); %载波调制 rf_rec_qam16_n=awgn(rf_rec_qam16,SNR(i),measured); %加噪声 [rec_qam16_rx base_rec_rx]=CarrierDemod(fd,fs,fc,f,rf_rec_qam16_n); %载波解调 bit_rec_rx=QamDemod(rec_qam16_rx,16); %MQAM解调 [num_qam16,perr_qam16_rec(i

5、)]=biterr(bit_tx,bit_rec_rx);%误码率 qam16_data_rec(i,:)=rec_qam16_rx; %scatterplot(rec_qam16_rx); %星形映射16QAM rf_star_qam16=CarrierMod(fc,f,base_star); %载波调制 rf_star_qam16_n=awgn(rf_star_qam16,SNR(i),measured); %加噪声 [star_qam16_rx base_star_rx]=C

6、arrierDemod(fd,fs,fc,f,rf_star_qam16_n); %载波解调 bit_star_rx=StarQamDemod(star_qam16_rx); %MQAM解调 [num_qam16,perr_qam16_star(i)]=biterr(bit_tx,bit_star_rx);%误码率 qam16_data_star(i,:)=star_qam16_rx; %scatterplot(star_qam16_rx); end %% 理论误码率计算 SNRtheo=0:

7、0.1:length(SNR); for i=1:length(SNRtheo) SNRdec=10.^(SNRtheo(i)/10); theo_perr_qam16(i)=(3/8)*erfc(sqrt(SNRdec*2/5)); end %% 基带波形 N=200; n=1:N; t=1:N*10; %发送端波形 figure; stem(n,bit_tx(n)); title(发送序列); %发送序列 figure(Name,发送端基带信号); subplot(411); plot(t,real(base_rec(t)))

8、; title(方形映射-Q路); subplot(412); plot(t,imag(base_rec(t))); title(方形映射-I路); subplot(413); plot(t,real(base_star(t))); title(星形映射-Q路); subplot(414); plot(t,imag(base_star(t))); title(星形映射-I路); %接收端波形 figure; subplot(211); stem(n,bit_rec_rx(n)); title(方形接收序列); subplot(212); stem

9、(n,bit_star_rx(n)); title(星形接收序列); figure(Name,接收端基带信号); subplot(411); plot(t,real(base_rec_rx(t))); title(方形映射-Q路); subplot(412); plot(t,imag(base_rec_rx(t))); title(方形映射-I路); subplot(413); plot(t,real(base_star_rx(t))); title(星形映射-Q路); subplot(414); plot(t,imag(base_star_rx(t)))

10、; title(星形映射-I路); %基带眼图 N1=20000; Tn=f/fd; eye_rex=base_rec(1:N1); eyediagram(eye_rex,Tn*4,Tn); title(方形基带眼图); eye_star=base_star(1:N1); eyediagram(eye_star,Tn*4,Tn); title(星形基带眼图); %% 接收端星座图 %scatterplot(qam16_data_rec(12,:)); figure(Name,方形16QAM接收端星座图); for i=3:3:12 su

11、bplot(2,2,i/3); plot(real(qam16_data_rec(i,:)),imag(qam16_data_rec(i,:)),.); xmax=5;axis([-xmax xmax -xmax xmax]) title([Snr=,num2str(SNR(i)), dB]); end figure(Name,星形16QAM接收端星座图); for i=3:3:12 subplot(2,2,i/3); plot(real(qam16_data_star(i,:)),imag(qam16_data_star(i,:)

12、),.); xmax=3;axis([-xmax xmax -xmax xmax]) grid on; title([Snr=,num2str(SNR(i)), dB]); end %% 功率谱密度 f_plot; %% 误码率分析 %16QAM误码率曲线 figure(Name,16QAM误码性能对比); % semilogy(SNRtheo,theo_perr_qam16); % hold on; semilogy(SNR,perr_qam16_rec,*); hold on; semilogy(SNR,perr_qam16_star,o

13、); xlabel(SNR in dB); ylabel(Prb of Err); legend(方形16QAM,星形16QAM); title(16QAM误码性能对比); %------------------------------------------------------------------------------- %% 基带成型 function base_info=base_shape(fd,fs,f,seq_16QAM) %平方根升余弦滤波器,滚降系数0.5，延迟3个采样点 flt=rcosine(fd,fs,sqrt,0.5);

14、 %I路和Q路 seq_Q=real(seq_16QAM); seq_I=imag(seq_16QAM); %增采样 R=fs/fd; up_seq_Q=upsample(seq_Q,R); up_seq_I=upsample(seq_I,R); %升余弦调制 rcos_Q=conv(up_seq_Q,flt); rcos_I=conv(up_seq_I,flt); %提升 rcos_Q_up=interp(rcos_Q,f/fs); rcos_I_up=interp(rcos_I,f/fs); base_info

15、=rcos_Q_up+j*rcos_I_up; %-------------------------------------------------------------------- %% 载波解调 function [data_rx base_rx]=CarrierDemod(fd,fs,fc,f,receive) %% 分两路乘正交高频载波 rc_length=length(receive); flt=rcosine(fd,fs,sqrt,0.5); t=0:rc_length-1; rc_Q=receive .* sin(2*pi*fc*t/f);

16、rc_I=receive .* cos(2*pi*fc*t/f); %减采样后根升余弦匹配滤波，注意对齐采样点 down_Q=downsample([0 rc_Q],f/fs); down_I=downsample(rc_I,f/fs); low_Q_rcos=conv(down_Q,flt); low_I_rcos=conv(down_I,flt); base_rx=low_Q_rcos(1:length(low_I_rcos))+j*low_I_rcos; %两次根升余弦滤波延迟，定位初始信号位置 %delay+1:end-delay-1 R=fs/fd; de

17、lay=3*R*2; rc_Q_seq=(downsample(low_Q_rcos(delay+1:end-delay-1),R)); rc_I_seq=(downsample(low_I_rcos(delay+1:end-delay-1),R)); %类型转换 data_rx=rc_Q_seq+j*rc_I_seq; %-------------------------------------------------------------------------- %% 载波调制 function transmit=CarrierMod(fc,f,base

18、) %载波调制 t=0:length(base)-1; high_freq_Q=real(base) .* sin(2*pi*fc*t/f); high_freq_I=imag(base) .* cos(2*pi*fc*t/f); transmit=high_freq_Q+high_freq_I; %------------------------------------------------------------------------------ % % QAM解调程序，将MQAM码元还原为二进制数据 % 入口参数：data

19、_QAM：QAM码元数据 % M_QAM:MQAM中M的大小 % 出口参数：二进制数据比特流 %------------------------------------------------------------------------ function data_out=QamDemod(data_QAM,M_QAM) k=log2(M_QAM);%每个M进制码元的bit数 data_len=length(data_QAM);%码元长度 %----------------------------------

20、--------------------------------- %QAM信号放缩至与发送端相同比例 data_temp=data_QAM(find(real(data_QAM>0))); aver=mean(real(data_temp)); data_Qam_temp=data_QAM/aver*(2^(k/2-1)); %------------------------------------------------------------------------ %平移到第一象限 data_Qam_temp2=(data_Qam_temp+(2^(k/2)-1)*(1+

21、j))/2; %---------------------------------------------------------------------- %将实部虚部分别映射为二进制数据 %实部 data_real=round(real(data_Qam_temp2));%实部判决 data_real(find(data_real>(2^(k/2)-1)))=2^(k/2)-1;%大于2^(k/2)-1的数据判定为2^(k/2)-1 data_real(find(data_real<0))=0;%小于0的数据判为0 bit_real=abs(dec2bin(data_real

22、))-0; %虚部 data_imag=round(imag(data_Qam_temp2));%虚部判决 data_imag(find(data_imag>(2^(k/2)-1)))=2^(k/2)-1;%大于2^(k/2)-1的数据判定为2^(k/2)-1 data_imag(find(data_imag<0))=0;%小于0的数据判为0 bit_imag=abs(dec2bin(data_imag))-0; %------------------------------------------------------------------------ %还原为二进制比特流

23、 bit_rec=[bit_real,bit_imag]; data_out=reshape(bit_rec,1,data_len*k); %------------------------------------------------------------------------------------------------------------- % % QAM调制程序，实现二进制到MQam调制 % 入口参数：binary：二进制数据 % M_QAM:MQAM中M的大小 %

24、 返回参数：MQAM码元 %------------------------------------------------------------------------ function data_M = QamMod(binary,M_QAM) k=log2(M_QAM);%每个M进制码元的bit数 data_len=length(binary);%比特长度 binary_rec=reshape(binary,k,data_len/k);%转化为data_len/k行，k列，的矩阵，以便转化为16进制M进制 %计算实部 data_str1=num2str(

25、binary_rec(:,1:k/2)); data_m_real=bin2dec(data_str1); %计算虚部 data_str2=num2str(binary_rec(:,k/2+1:k)); data_m_imag=bin2dec(data_str2); %实部虚部映射到MQam data_M=((data_m_real*2-2^(k/2)+1)+j*(data_m_imag*2-2^(k/2)+1)).; %----------------------------------------------------------------------------

26、----- %% 星形16QAM映射 function data_m16 = SrarQamMod(binary) %binary=randint(1,100);%产生随机序列 data_len=length(binary);%比特长度 binary_rec=reshape(binary,4,data_len/4);%转化为data_len/4行，4列，的矩阵，以便转化为16进制 data_str=num2str(binary_rec); data_dec=bin2dec(data_str); data_mm16=(floor(data_dec/8)+1).*exp(j*

27、45/180*pi*mod(data_dec,8)); data_m16=reshape(data_mm16,1,data_len/4); %------------------------------------------------------------------------------ %% 星形16QAM解调 function data_bit = StarQamDemod(qam_rev) %qam_rev=xing_qam16_noise(1:10); am=abs(qam_rev);%幅度判定 am(find(am>2))=2;%幅度大于2的判定为2

28、am(find(am<1.5))=1;%幅度大于2的判定为2 %相位判定 ang=angle(qam_rev)/pi*180;%将-180度到0度变为180度到360度 ang(find(ang<0))=ang(find(ang<0))+360; ang_n=round(ang/45); ang_n(find(ang_n>7))=0; data_dec=8*(round(am)-1)+ang_n; %data_dec(find(data_dec>15))=15;%大于15的判定为15 %data_dec(find(data_dec<0))=0;%小于0的判定为0 data_bit_rec=dec2bin(data_dec); data_bit=reshape(data_bit_rec,1,length(qam_rev)*4)-0;